The Surprising Reason We Have a Memory

Michio Kaku is the co-founder of String Field Theory and is the author of international best-selling books such as Hyperspace, Visions, and Beyond Einstein. Michio Kaku is the Henry Semat Professor in Theoretical Physics at the City University of New York. This article is excerpted from his new book, The Future of the Mind.

Vision, which we think happens effortlessly, requires billions of neurons
firing in sequence, transmitting millions of bits of information per second.
And remember that we have signals from five sense organs, plus emotions
associated with each image . All this information is processed by the
hippocampus to create a simple memory of an image. At present, no machine
can match the sophistication of this process, so replicating it presents an
enormous challenge for scientists who want to create an artificial hippocampus
for the human brain.

If encoding the memory of just one of the senses is such a complex process,
then how did we evolve the ability to store such vast amounts of information
in our long-term memory? Instinct, for the most part, guides the behavior of
animals , which do not appear to have much of a long-term memory. But as
neurobiologist Dr. James McGaugh of the University of California at Irvine
says, “The purpose of memory is to predict the future,” which raises an
interesting possibility. Perhaps long-term memory evolved because it was
useful for simulating the future. In other words, the fact that we can remember
back into the distant past is due to the demands and advantages of simulating
the future.

Indeed, brain scans done by scientists at Washington University in St. Louis
indicate that areas used to recall memories are the same as those involved in
simulating the future . In particular, the link between the dorsolateral
prefrontal cortex and the hippocampus lights up when a person is engaged in
planning for the future and remembering the past. In some sense, the brain is
trying to “recall the future,” drawing upon memories of the past in order to
determine how something will evolve into the future. This may also explain
the curious fact that people who suffer from amnesia —such as HM— are
often unable to visualize what they will be doing in the future or even the very next day.

“You might look at it as mental time travel— the ability to take thoughts about
ourselves and project them either into the past or into the future,” says Dr.
Kathleen McDermott of Washington University. She also notes that their study
proves a “tentative answer to a longstanding question regarding the
evolutionary usefulness of memory. It may just be that the reason we can
recollect the past in vivid detail is that this set of processes is important for
being able to envision ourselves in future scenarios. This ability to envision
the future has clear and compelling adaptive significance.” For an animal, the
past is largely a waste of precious resources since it gives them little
evolutionary advantage. But simulating the future, given the lessons of the
past, is an essential reason why humans became intelligent.

Excerpt from THE FUTURE OF THE MIND: THE SCIENTIFIC QUEST TO UNDERSTAND, ENHANCE, AND EMPOWER THE MIND by Michio Kaku, copyright 2013 by Michio Kaku. Used by permission of Doubleday, an imprint of the Knopf Doubleday Publishing Group, a division of Random House LLC. All rights reserved.